Will the next Republican nominee for President support gay marriage? It is a question that was unthinkable years ago, but amid a rapid shift in public opinion and demographics, it is being seriously considered in GOP circles.

“At the rate this issue is changing within the party, I think it’s not out of the question,” said Margaret Hoover, a former George W. Bush White House aide and one of the leading Republican Party operatives calling for the recognition of same-sex marriages. “It’s not if, it’s when — 2016 or 2020,” said another Republican operative.

The confidence to even ask the question is buoyed by a sea change in Republican Party thinking on the issue over the past several weeks. Dozens of top party operatives and former politicians — including six former aides to Mitt Romney and seven current or former members of Congress — have signed onto an amicus brief supporting the legal challenge to California’s Proposition 8 in advance of oral arguments on the constitutionality of the gay-marriage ban. Ohio Senator Rob Portman endorsed gay marriage on Friday after revealing that his son is gay. And new polling has brought to light a clear shift in the opinions of Republicans and the nation at large.

Indeed, that was one of the key recommendations in the Republican Party’s 2012 autopsy: a critical need to soften the party’s position on gay marriage, which has become a threshold issue for many young voters.

On Monday, Republican National Committee Chairman Reince Priebus supported Portman’s decision to change his mind on gay marriage when asked how the party will try to reach out to gays and young voters into the fold, saying it was no different than embracing the so-called Liberty movement championed by Senator Rand Paul. “I think Senator Portman made some pretty big inroads last week,” Priebus told reporters. “I think it’s about being decent. I think it’s about dignity and respect, that nobody deserves to have their dignity diminished, or people don’t deserve to be disrespected. I think that there isn’t anyone in this room — Republican, Democrat, in the middle — that doesn’t think that Rob Portman, for example, is a good, conservative Republican. He is. And we know that.”

That comes barely six months since the party ratified its 2012 platform at the Republican Convention including a reaffirmation of its call for a marriage amendment to the Constitution and a defense of the Boy Scouts of America for banning gay scouts and troop leaders. “We applaud the citizens of the majority of states which have enshrined in their constitutions the traditional concept of marriage, and we support the campaigns under way in several other states to do so,” the platform states. “We condemn the hate campaigns, threats of violence, and vandalism by proponents of same-sex marriage against advocates of traditional marriage and call for a federal investigation in to attempts to deny religious believers their civil rights.”

“Our report speaks for one direction for the future of the party,” said Ari Fleischer, Bush’s press secretary and an author of the RNC review of the 2012 election. “When they gather to write the next platform, they are hopefully going to take into account what we’re saying [and change].”

But evangelical opponents of same-sex marriage are predicting a swift and powerful backlash against the establishment driving the moderation.

“Obviously, this RNC report was designed to pander to the GOP’s wealthy elites, the same ones who encouraged Mitt Romney to ‘tone down his social-issues talk,’” Family Research Council president Tony Perkins said in an e-mail to supporters. “Unfortunately for them, money doesn’t decide elections; people do. And the vast majority of the GOP base believes that marriage is a non-negotiable plank of the national platform.”

“I think it’s a media-generated narrative a week before the Supreme Court hears the case because the media tends to agree that same-sex marriage should be a constitutional right,” said Thomas Peters, communications director for the National Organization for Marriage. “There has been no change. Republicans who come out for gay marriage get a big check from [the pro-gay-marriage Republican donor] Paul Singer, a couple of weeks of news cycles, and then you quietly get destroyed in primaries.”

But an ABC News/Washington Postpoll released this week found that 52% of Republicans and Republican-leaning independent voters ages 18 to 49 back gay marriage — the highest percentage ever recorded — with 81% of 18- to 29-year-olds supporting overall.

Alex Lundry, the director of data science for Romney’s campaign and a signatory to the amicus brief, described the past several weeks as a “pivotal moment” for the Republican Party on the issue, highlighting growth in a 24% increase in support among white evangelical Protestants and a 23% increase in self-identified conservatives over the past nine years.

“Evangelical millennials are 64% in favor of allowing same-sex couples to marry,” he said. “This idea that there’s going to be a grassroots surge in opposition to establishment republicans who are coming out for this is hyperbolic. They’re moving, everyone’s moving.”

At the 2012 Conservative Political Action Conference — to which Republican gay-marriage-supporting groups like GOProud were formally not invited — a panel urging moderation on the issue packed a small conference room. The organization’s executive director Jimmy LaSalvia told the assembled audience that the party needs to accept LGBT Americans if it wants to stop hemorrhaging young voters. “There are a few in our movement who just don’t like gay people, and in 2013 that’s just not O.K. anymore,” he said. “If we don’t publicly stand up to the bigots, then everyone assumes we agree with them … How can we expect [young voters] to listen if they think that conservatives hate their families and friends.”

The drumbeat of gay-marriage supporters within the Republican Party stands in contrast to their silence nationally on the issue during the 2012 election cycle, when they focused their efforts on the handful of states with ballot initiatives or amendments on the issue up for consideration. Advocates say they were fearful that forcing the issue would give more ammunition to Democrats to brand the Republican Party as out of touch in the form of social conservative denouncements.

And for the establishment Republicans who support gay marriage, the election reinforced their desire to push the party to moderate. “We were trying to have an election about the economy, and [to have this conversation within the party] would have been a distraction,” said David Kochel, an Iowa-based Romney adviser and one of many in the party establishment who have called for an embrace of same-sex marriages. “But that said, Obama wasn’t running a race about the economy. He was just killing us with this once he came out for same-sex marriage.”

“We all have been called bigots and homophobes because of the R next to our names, but we’re just not in a position to set policy yet,” said one swing-state operative who is supportive of gay marriage but won’t speak out publicly for professional reasons. “We’re the ‘elephants in the closet.’”

Even a casual survey finds that the vast majority of the Republican establishment under the age of 40 — the professional communicators, strategists and policy wonks — are all quietly supportive of same-sex marriage.

And while some of the “elephants” are coming out — Brad Dayspring, communications director for the National Republican Senatorial Committee and a former aide to House majority leader Eric Cantor, publicly voiced his opposition to bans on gay marriage after the Portman announcement — it’s equally true that Republican candidates and elected officials have been slower to move on the issue than the people who work for them.

But a growing caucus of Republican operatives isn’t so sure, pointing to demographic trends. “I don’t think we need to see Republican elected officials pull a Portman and change their minds,” said one operative. “I think you will see less of an effort to talk about marriage, less of a need to push legislative actions on the floor, more tolerance for differing opinions on the issue. In the long term, Gen Y and millennial Republican candidates are going to be for it.”

And can a Republican in support of gay marriage win the notoriously conservative Iowa caucuses? “Absolutely they can — assuming they have the right conservative message,” Kochel, who ran Romney’s campaign in the state, said, pointing to the growth of the libertarian movement in the state.